Transcript Biochemical Basis of Life FDx

Biochemical Basis of Life
Atoms
 Atoms are the basic units of matter.
 The atom is the smallest particle of a substance that
still remains the properties of that substance.
 Atoms are composed of protons, neutrons, and
electrons.
Atoms (continued)
 Protons: positive charge
 Neutrons: no charge
 Electrons: negative charge
 Protons and neutrons have about the same mass and
are found in the center of the atom, the nucleus.
 Electrons are very light and in constant motion
surrounding the nucleus.
Elements
 A chemical element is a pure substance that
consists entirely of one type of atom.
 More than 100 are currently known to exists;
however, only about 20 to 24 are commonly found in
living organisms.
Symbols for Elements
 Chemists use symbols of one or two letters to
represent elements. The first letter is always
capitalized. If there is a second letter, it is not
capitalized.
 C represents carbon.
 Al represents aluminum.
 Au represents gold. (The Latin name for gold is
aurum.)
Periodic Table
 There are four pieces of information for each
element.
Atomic Number
Atomic Symbol
Atomic Name
Atomic Mass
Periodic Table
 Atomic number is the number of protons (or
electrons)
 Atomic mass is the mass of the nucleus, protons
and neutrons.
Compounds
 A compound is a substance formed by the chemical
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combination of two or more elements in definite
proportions.
The composition of compounds are represented by a
kind of shorthand known as a chemical formula.
H20: 2 elements of hydrogen and 1 element of
oxygen
The physical and chemical properties of a compound
are usually very different from the individual
elements.
http://vimeo.com/4433312
Chemical Bonds
 The atoms in compounds are held together by
various types of chemical bonds.
 Bond formation involves the electrons that surround
each atomic nucleus. The tendency of elements to
combine and form compounds depends on the
number and the arrangement of electrons in their
outermost energy level.
 The main types of bonds are ionic and covalent
bonds.
Ionic Bonds
 An ionic bond is formed when one or more
electrons are transferred.
 An atom that loses electrons becomes positively
charged. An atoms that gains electrons becomes
negatively charged. Atoms with a charge are called
ions.
 Ionic bonds form between sodium and chlorine to
form table salt (NaCl).
Electrons
 Electrons have energy levels surrounding the
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nucleus.
1st energy level has 2 electrons
2nd energy level has 8 electrons
3rd energy level has 18 electrons
4th through 7th energy levels like bond in 8 or groups
of 8 or have full electron shells. (An electron’s happy
state is 8: octet rule)
Ionic Bonds
Protons +11 Protons +17
Electrons - 11 Electrons - 17
Charge
0 Charge
0
Protons +11 Protons +17
Electrons - 10 Electrons -18
Charge
+1 Charge -1
Covalent Bonds
 A covalent bond is formed when electrons are
shared by atoms.
 When atoms of the same element join together, they
also form a molecule.
 Covalent bonds form between hydrogen and oxygen
to form H2O, water.
What type of bond is the cartoon illustrating?
Answer
 The cartoon is illustrating an ionic bond. An ionic
bond is an electrical attraction between two
oppositely charged atoms. The positively charged
atoms are inside the classroom are attracted to the
negatively charged atoms on the outside of the
window.
Properties of Water
 A water molecule (H20), is made up of three atoms:
two hydrogen and one oxygen.
 Water is one of the few compounds found in a liquid
state over most of the surface of Earth. In its solid
state, ice has a low density allowing objects to float.
 Water is polar. The charges are unevenly
distributed. The hydrogen end is positive and the
oxygen end is negative.
 Because water is a polar molecule, it is able to
perform multiple hydrogen bonds, which account for
many of water’s special properties.
Properties of Water
 The attraction between a hydrogen atom on one
water molecule and the oxygen atom on another
water molecule is called a hydrogen bond.
 Hydrogen bonds are not as strong as ionic or
covalent bonds, and they can form in other
compounds as well.
Properties of Water
 High Heat Capacity is the amount of heat energy
required to increase its temperature.
 Adhesion is an attraction between molecules of
different substances. Adhesion forms capillary action
which give water the ability to climb structures.
(Ex. Water in the stem of plant stalks)
 Cohesion is attraction between molecules of the
same substance. Cohesion causes water molecules to
be drawn together . This results in surface tension.
https://www.youtube.com/watch?v=HVT3Y3_gHGg
Properties of Water
 Surface tension –
cohesion of water with a
film-like quality on the
surface of a liquid
 Capillary action –
tendency of a liquid to
draw up into a narrow
tube due to the liquid’s
properties of cohesion
and adhesion
Solutions
 A solution is composed of two parts: solute and
solvent.
- In a salt water solution, table salt is the solute –
the substance that is dissolved.
- Water is the solvent – the substance in which the
solute dissolves.
 Water is the universal solvent.
 A homogenous mixture is a solution where the
substance looks the same throughout .
Van der Waals
 Van der Waals forces include attractions and
repulsions between atoms, molecules, and surfaces,
as well as other intermolecular forces.
 Geckos can stick to walls and ceilings because of Van
der Waals forces.
Let’s Practice
 Identify the property of water that best describes the
following statements:
1. Water forms raindrops as is flows through the air.
________________
2. Fish and other aquatic life are able to survive in
subzero temperatures. _______________
3. Water is able to ascend very tall trees.
______________
4. Many types of materials are able to be dissolved in
water. _________________
Answers
1. Water forms raindrops as is flows through
the air. Cohesion
2. Fish and other aquatic life are able to
survive in subzero temperatures. low
density of ice
3. Water is able to ascend very tall trees.
adhesion
4. Many types of materials are able to be
dissolved in water. polarity
Acids and Bases
 Some compounds break into ions when they dissolve
in water.
 An acid is any compound that forms hydrogen ions
(H+) in a solution.
 A base is a compound that produces hydroxide ions
(OH-) in a solution.
pH
 The pH scale is a measurement system used to
indicate the concentration of H+ ions in a solution.
 pH scale ranges from 0 to 14. 7 is neutral.
 Solutions with a pH below 7 are called acidic
because they have more H+ ions than OH- ions. The
lower the pH, the greater the acidity.
 Solutions with a pH above 7 are called basic because
that have more OH- ions than H+ ions. The higher
the pH, the more basic the solution.
Buffers
 The pH of the fluids within most cells in the human
body must generally be kept between 6.5 and 7.5 in
order to maintain homeostasis. If the pH is lower
or higher, it will affect chemical reactions that take
place within the cells.
 One of the ways that organisms control pH is
through dissolved compounds called buffers, which
are weak acids or weak bases that can react with
strong acids or bases to prevent sharp, sudden
changes in pH.
pH Scale
Practice #2 Use the diagram below to answer the following:
5. Which is more basic: blood or ammonia? _______
6. What is the pH of drain cleaner? ____________
7. Would a lemon have more hydrogen or hydroxide
ions? _____________
8. What is the pH of lemon?_______________
9. Is water an acid, a base, or neutral? ___________
Answers
5. Which is more basic: blood or ammonia? ammonia
6. What is the pH of drain cleaner?14
7. Would a lemon have more hydrogen or hydroxide
ions? hydrogen
8. What is the pH of lemon?2
9. Is water an acid, a base, or neutral? neutral
Let’s Practice - 3
10. John consumes large amounts of black coffee and
tomato juice daily. Sometimes these fluids cause
digestive discomforts, and he takes antacids to
reduce the symptoms. Use your knowledge of acids,
bases, and pH to explain why antacids reduce the
symptoms.
Answer
 Coffee and tomatoes are acidic fluids. Antacids are
bases. A base reacts with an acid to form a less acidic
product. Antacids help neutralize digestive juices by
changing its pH.
Carbon Compounds
 Carbon can bond with many elements, including
hydrogen, oxygen, phosphorus, sulfur, and nitrogen
to form the molecules of life.
 Carbon can share its electrons with other atoms to
form up to four covalent bonds.
 Carbon-carbon bonds can be single, double, or triple
covalent bonds.
 Chains of carbon atoms can even close up on
themselves to form rings.
Macromolecules
 Many of the molecules in living cells are very large
and known as macromolecules.
 Most macromolecules are formed by a process
known as polymerization through which large
compounds are built by joining smaller ones
together.
 The smaller units or monomers join together to form
polymers.
Polymer Train
monomer + monomer + monomer + monomer
Polymers
 Polymers are formed by dehydration synthesis
because water is given off.
 Polymers are broken apart by hydrolysis because
water is added.
Types of Macromolecules
 Carbohydrates
 Lipids
 Proteins
 Nucleic Acids
Macromolecules: Carbohydrates
Type
Structures
Monomers
Function
Sugar, starches,
and cellulose
Carbon:Hydrogen:
Oxygen
Glucose
Living things use
carbohydrates as
their main source
of energy.
Monosaccharide
1:2:1 ratio
C6H12O6
Disaccharides
Polysaccharides
Types of Carbohydrates
 Monosaccharide: one simple sugar. Examples are
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glucose, fructose(fruit sugar), galactose(milk sugar)
The formula for glucose is C6H12O6. Plants use this
during photosynthesis
Disaccharide: two simple sugars joined by a saccharide
bond. Examples are sucrose(table sugar), lactose(milk
sugar), and maltose (malt beverage sugar)
Polysaccharide: three or more monosaccharides
combined. Examples are cellulose(cell walls), chitin
(exoskeleton), glycogen (stores glucose in liver cells),
starch (stores glucose in roots of plants)
http://www.youtube.com/watch?v=QckfYvIlVu4
Isomers
 Isomers have the same elements, but are arranged
differently.
 An example of an isomer is glucose and fructose.
Macromolecules: Lipids
Type
Structure
Fats, Oils, Waxes
Carbon, Hydrogen, 3 Fatty Acids and
and Oxygen
Glycerol
NOT in the same
1:2:1 ratio as
carbohydrates
Monomer
Function
Lipids form part of
biological
membranes, store
energy, help
insulate the body,
and cushion and
protect organs.
Lipids
 Lipids are made of glycerol and three fatty acids.
 Lipids contain fewer oxygen than carbohydrates
 Lipids are used for protection, cushion, structure,
insulation, and long term energy storage.
 Two main types of lipids are fatty acids and
phospholipids.
 http://www.youtube.com/watch?v=3xF_LK9pnL0
2 Types of Fatty Acids
 Saturated: solid at room temperature, example
animal fats
 Unsaturated: liquids at room temperature,
example vegetable oil
Phospholipids
 Phospholipids make up cell membranes.
 They are like fatty acids that contain phosphorus.
Macromolecules: Proteins
Type
Structure
Monomer
Antibodies,
Carbon, Hydrogen, Amino Acids (20)
Muscles, Enzymes, Oxygen, and
and Hair.
Nitrogen
Function
Proteins control
rate of reactions,
regulate cell
processes, form
cellular structures,
and fight diseases.
Proteins
 Proteins are composed of carbon, hydrogen, oxygen,
and nitrogen with sulfur and two amino acids
 The building blocks of protein are amino acids held
together by a peptide bond.
 Examples of proteins are antibodies, muscles,
enzymes, and hair.
 http://www.youtube.com/watch?v=w-ctkPUUpUc
Macromolecules: Nucleic Acids
Type
Structure
Monomer
DNA
RNA
Carbon, Hydrogen, Nucleotides
Oxygen, Nitrogen,
Phosphorus
Function
Nucleic acids store
and transmit
genetic
information.
Nucleic Acids
Nucleic acids are used for controlling cellular activities
and making protein (genes)
Nucleic acids are made of:
 a simple sugar: deoxyribose for DNA and ribose for
RNA
 phosphate group
 nitrogen base: adenine, cytosine, guanine, and
thymine for DNA and adenine, cytosine, guanine,
and uracil for RNA
 http://www.youtube.com/watch?v=jKMwLrbYyJ0
Organic Substances of the Body
Organic
Compound
(Polymer)
Carbohydrates
Elements
Building Blocks
(monomer)
C, H, and O
(H:O ratio of
2:1)
Simple sugars
Lipids
C, H and O
Glycerol and
Fatty Acids
Proteins
C, H, O, and
N
Amino Acids
Nucleic Acids
(DNA and RNA)
C, H, O, N
and P
Nucleotides
(monosaccharaids)
Let’s Practice -4 Matching #11
Answer for Practice -4 #11
Chemical Reactions
•Chemical reaction is a process that changes one set of
chemicals into another set of chemicals.
•Reactants are substances that go into a chemical reaction.
•Products are substances that result from a chemical
reaction.
•Reactants and products are separated in a chemical
reaction by a yields sign .
Enzymes
 Activation energy is the term used to describe the energy needed
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to get a reaction started. A catalyst is a substance that accelerates
the rate of a chemical reaction.
Enzymes are proteins that act as biological catalysts. Enzymes do
not cause reactions to happen. They speed up chemical reactions
that take place in cells.
Enzymes act by lowering activation energies, which has a dramatic
effect on how quickly reactions are completed. Without enzymes the
reactions of the cells would proceed very slowly.
Enzymes are never used up in the reaction. They can be used over
and over again.
Enzymes get their names from the substances they act on and on
the action of the enzyme and end in “ase.”
Example: Lipase – breaks down a lipid.
How Enzymes Work
 Enzymes are very specific, generally catalyzing only
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one chemical reaction.
The reactants of the enzyme-catalyzed reactions are
known as substrates.
The substrates bind to a site on the enzyme called
the active site.
The active site and the substrate have
complementary shapes.
The fit is so precise the active site and substrate are
often compared to a lock and key.
Enzyme Regulation
 Temperature – Enzymes produced by the human
cells generally work best at temperatures close to
37°C, the normal temperature of the human body.
 pH – Enzymes work best at certain pH values. For
example, the stomach enzyme pepsin, which begins
protein digestion, works best under acidic
conditions.
 Regulatory Molecules- The activities of most
enzymes are regulated by molecules that carry
certain chemical signals within cells, switching
enzymes “on” or “off” as needed.
Let’s Practice – 5 Label as enzyme, active site,
products, substrate (reactants) , and enzymesubstrate complex (one is used twice). #12
Answers #12
Review
13. The effect of pH on a certain enzyme is shown in
the graph below:
At what pH would the enzyme be most effective?
A. Above 10
B. between 8 and 10
C. Between 5 and 7
D. below 5
Review
13. The effect of pH on a certain enzyme is shown in
the graph below:
At what pH would the enzyme be most effective?
A. Above 10
B. between 8 and 10
C. Between 5 and 7
D. below 5
Review
14. An enzyme and four different molecules are shown
in the diagram below:
The enzyme would most likely affect reactions
involving:
A. molecule A, only
B. molecule D, only
C. molecules B and D
D. molecules A and C
Review
14. An enzyme and four different molecules are shown
in the diagram below:
The enzyme would most likely affect reactions
involving:
A. molecule A, only
B. molecule D, only
C. molecules B and D
D. molecules A and C
Review
15. Ice floats on a lake. This characteristic of water is
responsible for
A. Suffocation of aquatic organisms
B. Mixing a lake’s thermal layers
C. Preventing a lake from freezing solid
D. Altering migration patterns of fish
Review
15. Ice floats on a lake. This characteristic of water is
responsible for
A. Suffocation of aquatic organisms
B. Mixing a lake’s thermal layers
C. Preventing a lake from freezing solid
(High Heat Capacity is the amount of heat
energy required to increase its temperature.)
D. Altering migration patterns of fish
Review
16. Proteins are formed from monomers (subunits)
called:
A. Nucleic acids
B. Fatty acids
C. Nucleotides
D. Amino acids
Review
16. Proteins are formed from monomers (subunits)
called:
A. Nucleic acids (it’s a type of macromolecule)
B. Fatty acids (monomers of lipids)
C. Nucleotides (monomers for nucleic acids)
D. Amino acids
Review
17. Which of the following macromolecules are a
prominent part of animal tissues that function in
insulation, helping animals to conserve heat?
A. Carbohydrates
B. Lipids
C. Proteins
D. Nucleic Acids
Review
17. Which of the following macromolecules are a
prominent part of animal tissues that function in
insulation, helping animals to conserve heat?
A. Carbohydrates
B. Lipids
C. Proteins
D. Nucleic Acids